Questions for NRG Energy

- Keystone

 Unit Shut Downs

o Unit 2 was shut down from 9/8/12 through 11/4/12. What was the reason for the shut down?

o Unit 1 was shut down from 10/27/12 through 11/23/12, and then again from 11/27/12 through 12/8/12. What was the reason for the shut downs?

o How was the FGD wastewater treatment system being operated between 10/27/2012 and 11/4/2012, when both units at the plant were shut down? For example, please explain the following:

 Was newly generated wastewater being transferre d to the system?

 If so, please explain from which process this wastewater was generated.

 Was the FGD wastewater treatment system operating in some type of recirculation mode?

 How does the flow rate through the process during this time compare to the flow

r ate during normal operation?

 What chemicals were being added to the FGD wastewater treatment system during this time and what were the corresponding dosages of the chemicals?

 How do the chemical dosages used during this time compare to the dosages during

n ormal operation?

 Please explain any other changes regarding the operation of the FGD wastewater treatment system during this time.

 Why did the plant continue to discharge FGD wastewater during this period?

 Since Jan 2014, Keystone has been analyzing for a rsenic and other metals using modified 200.8 (characterized by NRG Energy as a “more sensitive analytical method”). ( See Feb 21 email from Stephen Frank)

o What is “modified 200.8”? Did it use a collision cell or DRC?

o Which analytes are being analyzed by 2 00.8?

o For what dates are 200.8 data available?

o What is RL and DL for arsenic using the 200.8 ?

o Are the arsenic observations detects or nondetects? What are the reported concentrations above the RL? Arsenic

o Confirm results f or 7/24/12 and 8/12/13 are detects (as shown by the lab reports)

. o W hy is the RL for 200.7 at 20 ug/L and not a much lower concentration?

o What is meant by ND (“U”) for following dates which have this note: “The analyte was not detected at or above the listed concentration, wh ich is below the laboratory quantitation limit” ...but there is no concentration listed other than the DL and RL

 4/10/12, 4/11/12, 4/12/12

o Why is there a single result using EPA Method 6020 (<5 ug/L on 2/21/13)?

 What version of 6020?

 Was the analysis run using a collision cell or dynamic reaction cell?

 Do the 5 dilutions suggest that an undiluted analysis would have RL of 1 ug/L?

 Why is there no lab report for the 6020 result?

o Keystone reported several J values in the data spreadsheet, but the J values do not appear to be reported in the lab reports :

 FGD Influent J values: 2/21/2012; 4/17/2012; 9/18/2012; 10/9/2012

 Outfall 101 J values: 6/5/2012; 6/26/2012; 7/3/2012; 7/31/2012; 9/5/2012; 8/19/2013; 9/3/2013; 10/21/2013

. o Keystone’s data spreadsheet includes two FGD influent results on 4/10/2012; however, there is only one laboratory report for the FGD influent for that date. EPA did not find a lab report with the reported value of 1,390 ug/L for the FGD influent on 4/10/1 2.

o The dilution factor for arsenic at Outfall 101 for several Dec 2013 samples ( 12/2/2013; 12/16/2013; 12/23/2013; 12/30/2013 ) were entered into the spreadsheet as 1, when the lab report shows 2.

 Mercury

o What is meant by ND (“U”) for following dates which have this note: “The analyte was not detected at or above the listed concentration, which is below the laboratory quantitation limit” ...but there is no concentration listed other than the DL and RL

 4/10/12, 4/11/12, 4/12/12

o Why is there a “U” qualifier for 4/15/1 3 instead of “J”? And why is it listed as a detected value (no “<” in Column J)? Confirm it is nondetected (either below the RL or DL).

o 4/15/13

– Entry suggests it is a detected value because there is no “<” indicator , but the 2500 ppt value is list ed in the J

- value column and the RL is 4000 ppt. Confirm this is ND.